Surface sulfur recovery



SURFACE SULFUR RECOVERY 3 Sheets-Sheet 1 Filed April 2, 1968 muses 0 23mm0 OR M D 0 T S T 5 F- X R E X JOHN A.SUTHERLAND RUEL C. TERRY ATTORNEYDec. 29, 1970 STQDDARD ETAL 3,551,333

SURFACE SULFUR RECOVERY Filed April 2, 1968 3 Sheets-Sheet 8 .m .D Wm JTML l N R EwEY m v w um su TsT ACY E XNL WE xwR \J NQE ATTORNEY Dec. 29,1970 Y STQDDARD ETAL 3,551,333

SURFACE SULFUR RECOVERY Filed Apriliz. 1968 S SheetS-Sheet s l I003 I0024 4002 |oo| SULFUR '2 WATER":

lNVENTORS:

A RUEL C..TER RY 3 WWW Flui- ATTORNEY United States Patent 3,551,333SURFACE SULFUR RECOVERY Xerxes T. Stoddard, Rosenberg, and John A.Sutherland and Rnel C. Terry, Houston, Tex., assignors to AlliedChemical Corporation, New York, N.Y., a corporation of New York FiledApr. 2, 1968, Ser. No. 718,143 Int. Cl. 801d 37/00 U.S. Cl. 210-69 7Claims ABSTRACT OF THE DISCLOSURE A process for the extraction of sulfurfrom ore at or near ground level in which the molten sulfur is passedthrough a bed in opposing direction to the flow of hot water.

This invention relates to a process for recovering sulfur from ore.

More particularly this invention relates to a process for recoveringsulfur from ore which is located at or near ground level, as will bedescribed in more detail hereinafter.

The mining and extraction of sulfur from ore (1) substantially below theground and (2) located at or near ground level have been historicallytwo separate problems of sulfur recovery.

In the case of mining and extraction of sulfur from ore minedsubstantially below ground level, a great deal of research andexperimentation has taken place, with the Frasch process, as disclosedfor example in U.S. Pat. 1,628,873, issued May 17, 1927 providing abasis for such sulfur extraction. On the other hand, in extraction ofsulfur from ore located at or near ground level, a number of uneconomicor impractical, processes heretofore have been devised, usually sobecause of mechanical complication, cost, or inefficiency in the amountof sulfur extracted as compared to the amount of sulfur present in theore. The extraction of sulfur from ore located at or near ground levelhas therefore been the subject of continued research.

The Frasch process of mining sulfur where it occurs in depositssubstantially below ground level is discussed in detail in the patent towhich we have previously referred. Generally, that process relies on thefact that agglomerating molten sulfur, which has become molten below theground in the deposits in which it occurs (as a result of heat exchangewith super-heated water which has been forced through these deposits),travels through the deposit under the action of gravity in a directionopposite to the movement of the lighter ore flushing water moving fromthe well bore through the deposit. The agglomerating or fusing moltensulfur arrives through the deposit at the point in the well bore whereit can be carried up, as a result of the pressure differential, to anabove ground location. We have devised a process and apparatus relyingon the same principles of physical chemistry to effect the separation ofthe sulfur from the gangue.

Generally speaking, our process for extracting sulfur from ore at ornear the ground surface is as follows:

Sulfur bearing ore located at or near ground level is usually stockpiledfor sulfur recovery therefrom; such sulfur from deposits usually of, butare not limited to, the surface sulfur, spring, volcanic, hydro-thermalfumarole or solfataric types, including the presently poorly regarded,low-yield (540%) variety. The ore is then crushed and ground and thenpumped (for example, as a slurry in hot water) or moved by a conveyer toa position for further treatment, to be discussed in detail hereinafter.The crushed and ground ore is mixed with hot water Patented Dec. 29,1970 and, preferably, steam to commence melting of the sulfur depositedin the ore. The slurry of water and sulfur containing ore is thenintroduced into a fusion chamber under pressure. The molten sulfur,because of its tendency to agglomerate (as a result of the physical factthat it, like mercury, has an aifinity for itself) tends to jointogether as it melts at the elevated temperature, which has been reachedin the elevated pressure in the chamber. The agglomerating molten sulfurpasses downward through a bed in the chamber under the influence ofgravity. Hot water is passed through said bed in a counter-currentdirection to the direction which the gangue (ore depleted of sulfur) andliquid sulfur tends to move. Since the molten sulfur is heavier than thewater, the liquid sulfur passes through the bed in a downward directionwhile the water is passing upward through the bed counter-currently. Asa result of preferential wetting, and the surface tension of theupwardly moving water, the gangue, even though heavier than water, isfloated and washed by the upwardly moving water and separated, up toseparation from the sulfur. The molten sulfur is then collected at apoint below the bed for transmission to a storage area, while thegangue, the ore from which the agglomerated molten sulfur has beenextracted, is carried by the water to be separated therefrom. The watermay then be re-circulated to be reused in the process just described. Asneeded, additional hot water may be added to the process.

The invention will now be described in more detail with relation to thefollowing drawings.

FIG. 1 shows a schematic illustration of the process for carrying outthe invention;

FIG. 2 shows a schematic of a second embodiment for carrying out theprocess described; and

FIG. 3 is a detailed showing of the bed employed.

In the figures of the drawing, like numerals indicate like or equivalentstructure throughout.

In FIG. 1, ore bearing sulfur 1 is shown at the extreme left awaitingprocessing for extraction of the sulfur deposited therein. Said ore hasbeen mined at or near the surface, or in such a manner as to not allowfor mining by the conventional Frasch process or its equivalent, alreadydescribed. In the embodiment shown in FIG. 1, the ore bearing sulfur isfed to hopper 4 through use of, for example, conventional truck and rampstructure (shown schematically at 2 and 3 respectively). The ore iscrushed to, for example, size, and ground to, for example, pass a 28mesh screen in the hopper 4, again by the use of conventional structure,and loaded, for example, on an inclined conveyor 5. In the alternativeto using an inclined conveyor the ground ore may be pumped as a slurryby a slurry pump or equivalent.

In this embodiment, the ore leaves the inclined conveyor at anappropriate height, of say feet, for reasons that will become apparent.Upon leaving the inclined conveyor the ore enters a hopper 6 which feedsinto a water column 7, in which the ore is mixed with water from line 25to form a slurry, said water at a temperature in the range of -200 F andpreferably of about 200 F. The mixing of the hot water and ore may beeffected by, for example, a Venturi jet mixer 8. It may be necessary toincrease the wettability of the gangue as compared to the sulfurcontained therein by introducing an acid, not shown, and tosimultaneously neutralize the acidity of the slurry by the addition of abase, not shown, such as lime.

The pressure at the bottom of the column 7 is about 53 p.s.i.g. in thecase of the drop of ore and water from the top of said column of 125 ft.previously mentioned. The slurry of water and crushed ore is moved bypump 9 through line 1002 toward fusion chamber 10, and preferably, mixedwith steam (from line 1003 connected to steam generator 11) to commencesubstantial melting of the sulfur in the ore. Recirculating hot water,through line 12, and preferably, steam from the steam generator 11, fromline 1003, introduced into the chamber serve to continue the melting ofthe sulfur deposited in the ore. As a result of the introduction of thehot water, and preferably the steam, and the fact that the slurry isunder pressure in the chamber the temperature within the fusion chamberreaches about 260 to 280 F., and preferably about 270 F.

At this temperature, substantially all of the sulfur deposited in thecrushed and ground ore slurry becomes molten, and as a result of itsafiinity for itself, as previously discussed, tends to agglomerate orfuse.

The sulfur passes through the porous filtering bed 13 under the actionof gravity. It may be directed toward said filtering bed by bafile 14.contemporaneously, hot water from the separator 27 is directed by pump15 through line 16 upwardly through said bed 13.

Because the molten sulfur is heavier than the water, the sulfur tends topass through the bed in counter-current direction to the movement of thewater. The water floats and entrains the gangue (which does not passthrough the bed) and removes it from cell 10 through line 17. Sulfurpassing through the bed is collected at the bottom of chamber 10 anddirected through line 18, which is valved at 19, to a collection pan 20,for example, for further filtering thereof or storage.

The gangue, moved by the water out of the chamber 10 through line 17separates in desanders and desilters (shown schematically at 21) and isremoved by suitable means, for example conveyor 22, to a place where itmay be dumped.

Pump 23 draws the water from separator 21 and preferably directs itthrough line 24 for re-circulation to the Venturi jet mixer 8 throughline 25 and through line 12 to the fusion chambers. Makeup and blendwater is supplied through line 26. To adjust the temperature in line 25to the desired temperature, for example 200 F., it is necessary tobalance the temperature of the makeup blend water with there-circulating water.

The wash water supplied through line 16 by pump 15 is, in thisembodiment, taken from line 12 after filtering to remove silt inseparator 27. Water may also be supplied from separator 27 to augmentthe heating of the sulfur and the ore in fusion chamber 10 before theagglomerating molten sulfur passes through the bed 13, said additionalsupply of water flowing through line 28.

One illustrative embodiment of the fusion chamber 10 and bed 13 is shownin more detail in FIG. 3. In said FIG. 3 a fusion chamber equipped withfiltering bed is schematically shown. In those instances whereapplicable, like numerals in FIG. 3 to those used in FIG. 1 identifyidentical features.

The chamber 10 preferably is enclosed by a demountable head 1001 whichhas inlets with lines leading thereto to receive the slurry through line1002 from pump 9 (of FIG. 1), the steam from steam generator 11 (ofFIG. 1) through line 1003, the recirculating hot water through line 12,and the silty water through line 28. The chamber may be stainless steelclad and is preferably insulated. Mounted, preferably detachably forcleaning or other servicing, is a baflle 14 for directing the slurrytoward the bed, the major portion of said baflle being mounted at anangle of, say 45 with the lower portion 2000 in the embodiment open topass the slurry. The bed 13 consists of a top screen 1005 of relativelylarge openings, for example about A"; a straining bed 1006, composed,for example, of rock granules, such as graded gravel and quartz pebbleabout to 1%" diameter, thereunder; and a bottom screen 1007 of, forexample about 1" diameter grid supporting the straining bed. Asupporting head 1008 supports the entire bed 13 and is itself supportedin any desired manner, say by trusses 1009. Hot water is introducedthrough the bottom screen 1007 upward through the straining bed 1006through hot water line 16 and, for example, nozzles 4005. Water andgangue is removed from chamber through line 17. Molten sulfur iscollected in pan area 1010 and taken from the chamber through line 18,valved at 19. A heating coil 1011, heated by steam or hot waterpreferably, may be routed through pan area 1010 to keep the sulfurmolten. Overflow from the bed 13 may be collected in pocket 1013 justpreceding line 17. The straining bed 1006 and screen 1005 thereabove arepreferably inclined, as shown, to direct the water and gangue toward theoutlet 17. A launder 1013 also may be provided at the lower end of topscreen to collect the gangue and discharge it into the outlet.

As is obvious from FIG. 3, slurry entering the chamber will be deflected(and agitated) by batfie 14 to flow across the inclined top screen 1005.Steam and re-circulating water enter the chamber, as indicated. Hotwater is directed upwardly through the bed 13. Agitation by saidupwardly flowing hot water wash keeps the gangue particles in suspensionas the agglomerating molten sulfur flows through the bed 13 by gravity,as diagramatically indicated in FIG. 3. The surface tension of theupwardly flowing water acts both to float off the gangue and to purifythe sulfur as coalescence takes place, or where coalescence has takenplace. Surface active agents added to the water may be used to furthercontrol the surface tension of the water, if desired.

Steam jets, 2001 and 2002, may be included in the chamber and at thedischarge (line 17), respectively, to insure that the ore will not hangup below opening 2000 and plug up the discharge line 17.

The chamber 13 shown in FIG. 3 is illustrative of the type of pressurevessel with bed necessary to accomplish the objectives of our invention.Structural details of said chamber may be altered. For example, but notshown, the baffle may be conical or the overflow and gangue collectingapparatus may be constructed completely around the perimeter of the bed13, with the bed not inclined as shown in FIG. 3. Preferably the chamberand other equipment should be made of or lined with corrosive resistantmaterial.

The process illustrated in FIG. 2 in most respects is similar to thatshown in FIG. 1, and employs chambers of the type described withrelation to FIG. 3. In the manner in which it is similar, thefunctioning thereof is apparent from the description with relation toFIG. 1 and description will not be repeated.

An alternate manner of feeding the sulfur ore to the hopper is shown inFIG. 2, as compared to FIG. 1. In FIG. 2 a belt conveyor 200 is showndiagrammatically as transporting ore from the stockpile to the hopper.

As previously discussed, one alternate way to the inclined conveyorshown in FIG. 1 of moving the ore to the fusion chamber is by pumping.In FIG. 2 the ore in the hopper 4 is again crushed and ground. Thesulfur containing ore is then mixed with water, flowing through line201, at a temperature in the range of about 175-200 F. and preferablyabout 200 F. Again, a Venturi jet mixer 400, for example, may beutilized to introduce the slurry into mixing chamber 202. The slurry ofground ore and hot water is then pumped by a pump 203 through line 204to the fusion chamber assembly. The line 204 is placed under pressure,for example, as the result of the use of a barometric leg 205 raised toan elevation similar to that described with relation to FIG. 1 andhaving a conventional overflow device 206. As described with relation toFIG. 1, steam is preferably added to the slurry of ground ore and hotwater, as through line 207, to commence the substantial melting of thesulfur, the steam being provided by steam generator 11, for example.

In FIG. 2, there is shown two fusion chambers 10 and 10. The chambers 10and 10' function alternately in the same manner as described withrelation to FIGS. 1 and 3, and are illustrative of a manifoldarrangement. As a result of employing the two fusion chambers 10 and 10,one

chamber may be cleaned or regenerated while the other is in service.

In the manner described with relation to FIG. 1, sulfur is removed fromthe bottom of the fusion chamber in operation (through line 18 or 18')which is valved at 19 or 19', respectively. The wash water, which movescounter-currently through the bed 13 or 13', is introduced through line16 or 16' from Wash water pump 15 while the tailings which are removedfrom chamber 10 or 10' by the wash water exits through line 17 or 17' toa similar separating device 21 to that described in FIGS. 1 and 3.

In a like manner to that described in FIG. 1 Water is re-circulatedthrough lines 24 and 20 1 to be mixed with the ground ore to form theslurry and to be supplied to the fusion chambers through line 12 and12'. Once again, in FIG. 2 blend and makeup Water may be added throughline 26 to make up for water lost in the process.

As shown, the tailings may be disposed of by engaging them in a slurryas the result of, for example, addition of water through line 210 andpump 211.

Steam may be added to the fusion chambers, as well as to the slurrydirected toward the chambers by directing steam from the generator 11through lines 207, and 212 to the chambers 10 and 10'.

Apparatus for recording temperature and pressure, located as shown inFIG. 2 at 4001 and 4002, respectively may be located in the equipmentshown in the figures as desired. For purposes of illustration, valvestructure is shown in FIG. 3 at points at which direction of flow may bealternative. It is emphasized that the incorporation of suitable valvestructure at the necessary points according to mechanical design is amatter within the skill of one versed in the art.

As a result of the re-circulation of the water described, our sulfurextraction process has a high thermal efficiency. Heat added to thewater in the fusion chamber, for example by steam injection results inthe high temperature in the chamber, which is under pressure, and allowsthe water to be re-circulated without additional re-heating.Furthermore, the process is continuous, without moving parts in thefusion chamber, and provides for a high recovery of sulfur from the ore,as much as 99% of the sulfur deposited in the ore being extracted, andis particularly adaptable to low grade sulfur ores. Since it is acontinuous process, relying on the physical principles utilized in theFrasch process for separation of the agglomerating sulfur from the ore,it is highly economic and elficient.

Although we have described, for the purpose of illustration, severalembodiments of our invention it is not our intention to be limited bythe details of such description but rather it is intended that theinvention may assume many different embodiments within the scope of thefollowing claim protection.

We claim:

1. A sulfur extraction process comprising the steps of mixing sulfurbearing ore with hot water to create a slurry, introducing said slurryinto a closed chamber containing a filter bed, introducing steam underpressure into said chamber with said slurry, maintaining said chamberunder pressure so that the temperature of the environment within thechamber rises to a level consistent With melting of substantially allthe sulfur, passing molten sulfur through said bed, passing heated waterinto the chamber counter-currently through said bed to movement of saidmolten sulfur through said bed, washing and suspending said ore fromwhich the sulfur has melted in said heated water after said water haspassed through the bed, removing molten sulfur which has passed throughsaid bed from the chamber, and removing from said chamber said ore fromwhich the sulfur has ben melted with said last mentioned water.

2. The process as set forth in claim 1, including the steps separatingsaid last mentioned water from said ore after removal from the chamber,and re-circulating said last mentioned water.

3. The process as set forth in claim 2, including the step of filteringat least a part of said re-circulated water to remove solid material,and passing said filtered water through said bed in said counter-currentdirection.

4. The process as set forth in claim 3, further including the step ofheating said slurry by adding steam under pressure thereto before it isintroduced into the chamber.

5. The process as set forth in claim 4, further including the step ofdeflecting the slurry in the chamber upon its entry therein in order toagitate it and direct it toward the bed.

6. The process as set forth in claim 5, further including the steps ofscreening the molten sulfur passing through said bed consecutively by anupper screen, a porous filtering bed, and a lower screen.

7. The process as set forth in claim 6, further comprising the step ofblending makeup water in said re-circulating Water.

References Cited UNITED STATES PATENTS 337,459 3/1886 Thornton 210-1832,044,214 6/1936 Jones 210-69 2,088,190 7/1937 Du Pont 23270X 2,746,8465/1956 Gruenewald et al. 23270X 2,750,000 6/1956 Williams et al. 210-71X3,072,463 1/1963 Owens, Ir. 23270X 3,080,220 3/1963 Lagatski 23270X2,237,711 4/1941 Morgan 210275X 3,337,054 8/1967 Sauer 210-266 JOHNADEE, Primary Examiner US. Cl. X.R.

